The use of evidence-based physical activity programs by public health practitioners is small, despite widespread knowledge of guidelines recommending their use. Public health organizations represent only one sector where such evidence-based programs may be disseminated;other sectors include fitness centers, worksites, and medical centers. To our knowledge, no study has examined the dissemination and implementation of such programs at the sector and organizational level. Active Living Every Day (ALED) is an evidence-based physical activity program that has been actively disseminated to four major sectors by Human Kinetics (HK), a leading publisher in the physical activity field. In this retrospective observational project, we propose to examine these processes in the dissemination of ALED: 1) sector and organization influences on decisions to adopt ALED and 2) organization influences on implementation and adaptation of ALED. Theoretical predictions about these processes based on the Diffusion of Innovations Model will be tested. We will assess sector-level influences (i.e. sector norms, actions by bellwether organizations, and intra-sector communication with other organizations) and organizational influences (i.e. knowledge of ALED and other physical activity programs, organizational values, decision-making processes, perceived innovation characteristics, and potential barriers to adoption) as predictors of ALED adoption in a case- control study (n=120 cases and 480 controls). We will also evaluate organization variables (i.e. opinion leadership, organizational decision-making, contextual supports, perceived innovation, compatibility with existing programs, adoption of other physical activity programs) associated with program implementation and describe adaptations made to ALED in an observational posttest-only study. We will analyze organizations that currently use ALED and those that have previously implemented the program but have discontinued using it (i.e., the cases in the case-control study;n=120) in the posttest-only study. Data will be obtained from (a) HK databases on promotional efforts, facilitator training, and purchase and use of ALED materials and online resources, (b) a survey of organization directors, and (c) follow-up interviews with directors at adopting organizations. The project will improve theoretical understanding of dissemination and provide empirical information for improving dissemination strategies for evidence-based prevention programs.